Electrophotographic imaging compositions, elements and processes are extensively described in technological literature, including patents. Generally, such compositions and elements are used in processes wherein the photoconductive element comprising a coated layer of a photoconductive composition, is image-wise exposed to activating radiation. A latent electrostatic charge image is formed on the coated layer. The charge image is developed and fixed, thereby forming a permanent record of the image.
Heterogeneous, "aggregate" photoconductive compositions and layers are useful in electrophotographic processes. Such photoconductive compositions are described in detail in U.S. Pat. No. 3,615,415, granted to Light on Oct. 26, 1971 and U.S. Pat. No. 3,679,408 granted to Kryman et al, July 25, 1972. In general, such a heterogeneous photoconductive composition is multi-phase, comprising a continuous phase of an electrically insulating polymeric binder having dispersed therein a particulate discontinuous phase referred to as aggregate photoconductive particles. Heterogeneous, aggregate compositions may optionally include one or more organic photoconductors dissolved in the continuous phase. The aggregate photoconductive particles are co-crystalline complexes of a pyrylium dye and a polymeric material. Heterogeneous, aggregate compositions are capable of high speeds and very high image quality. The aggregate photoconductive particle size varies from about 0.01 to about 25 microns. The predominant particle size in such compositions is typically greater than about 2 microns. This relatively large particle size impairs the high resolution capabilities of heterogeneous, aggregate photoconductive compositions. However the art does not teach a method for making aggregate photoconductive compositions having smaller particles in a narrower particle size distribution. Such compositions would have greater resolution capability and are therefore desirable.